I would like to add some demos to the tradelist, but they seem dodgy, mainly questions about the tapes, not so much about the covers. Don┤t have a camera at the moment = no photos of the tapes.
Anybody who is certain to own the real deal, info appreciated!

Rotting Christ┤s Ades Winds; I have seen a version where the cover has one more "opening" compared to the two covers in the picture. I have three Ades Wind┤s, none is on a pro-tape and I have a feeling that all three are boots. I added some red colour to confuse bootleggers

Corpsegrinder┤s - Demo 1991: Yellow covers but again on a normal tape, not a pro one.

Altar of Perversion - The Abyss Gate Re-opens. The covers & lyric sheet looks like the real deal, hand numbered, but the tape is once again normal copy tape.

Katharsis/Deathcult- split: Cover looks genuine, it has sombre┤s stamp on the white side & it is hand-numbered but the tape is not a pro.

The best way to be sure about originality is if you know the previous owners. If you get stuff by people like f. ex. Laurent Ramadier then you can be sure its original! And gather as much info as possible about the demo, the seller ( and his background, friends). Common sense and criticism is helping too.

I dont trust Neseblod. They have too good stuff and plenty of them. Also I know they sell bootlegs as original.

Might be true, lot┤s of unique items for sure.
When it comes to the Norwegian items they are selling, I am nevertheless pretty sure that most of them are genuine. Both the owners of Neseblod & several Norwegian musicians, have revealed in interviews, that the oop/bud/rare-items have found their way into the store through the hands of the musicians themselves---> in a quest to find money for expensive beer at Elm Street, they sell their releases (with signatures if it is their own release) to the store.
Maybe our Norwegian users can say something about resorting to Neseblod in times of financial crisis heh.